<!DOCTYPE html>
<html class="reftest-wait foo">
<title>View transitions: ensure :only-child is supported on view-transition-group</title>
<link rel="help" href="https://drafts.csswg.org/css-view-transitions-1/">
<link rel="author" href="mailto:khushalsagar@chromium.org">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style>
::view-transition {
  background-color: black;
}
html:only-child {
  background-color: black;
}
:root:only-child {
  background-color: black;
}
:only-child {
  background-color: black;
}
.foo:only-child {
  background-color: black;
}

::view-transition-group(root) {
  background-color: blue;
}
::view-transition-group(target) {
  background-color: blue;
}
::view-transition-group(*) {
  color: blue;
}

::view-transition-group(root):only-child {
  background-color: red;
}
::view-transition-group(target):only-child {
  background-color: red;
}
::view-transition-group(*):only-child {
  color: red;
}

</style>
<div id="target"></div>
<div id="target2"></div>

<script>
promise_test(() => {
  assert_implements(document.startViewTransition, "Missing document.startViewTransition");
  return new Promise(async (resolve, reject) => {
    let transition = document.startViewTransition();
    transition.ready.then(() => {
      let style = getComputedStyle(document.documentElement, "::view-transition-group(root)");
      if (style.backgroundColor == "rgb(255, 0, 0)" && style.color == "rgb(255, 0, 0)")
        resolve();
      else
        reject(style.backgroundColor + " and " + style.color);
    });
  });
}, ":only-child should match because ::view-transition-group is generated for root element only");

promise_test(() => {
  assert_implements(document.startViewTransition, "Missing document.startViewTransition");
  return new Promise(async (resolve, reject) => {
    target.style.viewTransitionName = "target";
    let transition = document.startViewTransition();
    transition.ready.then(() => {
      let style = getComputedStyle(document.documentElement, "::view-transition-group(root)");
      if (style.backgroundColor == "rgb(0, 0, 255)" && style.color == "rgb(0, 0, 255)")
        resolve();
      else
        reject(style.backgroundColor + " and " + style.color);
    });
  });
}, ":only-child should not match because ::view-transition-group is generated for multiple elements");

promise_test(() => {
  assert_implements(document.startViewTransition, "Missing document.startViewTransition");
  return new Promise(async (resolve, reject) => {
    document.documentElement.style.viewTransitionName = "none";
    target.style.viewTransitionName = "target";
    let transition = document.startViewTransition();
    transition.ready.then(() => {
      let style = getComputedStyle(document.documentElement, "::view-transition-group(target)");
      if (style.backgroundColor == "rgb(255, 0, 0)" && style.color == "rgb(255, 0, 0)")
        resolve();
      else
        reject(style.backgroundColor + " and " + style.color);
    });
  });
}, ":only-child should match because ::view-transition-group is generated for sub element only");

promise_test(() => {
  assert_implements(document.startViewTransition, "Missing document.startViewTransition");
  return new Promise(async (resolve, reject) => {
    document.documentElement.style.viewTransitionName = "none";
    target.style.viewTransitionName = "target";
    target2.style.viewTransitionName = "target2";
    let transition = document.startViewTransition();
    transition.ready.then(() => {
      let style = getComputedStyle(document.documentElement, "::view-transition-group(target)");
      if (style.backgroundColor == "rgb(0, 0, 255)" && style.color == "rgb(0, 0, 255)")
        resolve();
      else
        reject(style.backgroundColor + " and " + style.color);
    });
  });
}, ":only-child should not match because ::view-transition-group is generated for multiple sub elements");
</script>
